Into a life cut short by a heart attack at the age of 63, Elaine Paintin packed three quite different phases of activity, as arts administrator, civil servant at the Department of National Heritage, and director of the Marc Fitch Fund. In each role she achieved a great deal that will be of lasting value for the arts, archaeology and local history of Britain. The second phase was the shortest of all: her secondment as civil servant with responsibility for drafting and getting through parliament the Treasure Act 1996. This major extension of the ancient law of treasure trove has resulted in the saving for the public of hundreds of buried antiquities.

Elaine was born and brought up in Oxford, where her father, Leslie, worked in the council's planning department. She would have been the first to declare her debt to her teachers at Milham Ford school in Oxford. At that stage, too, she began an intermittent political involvement, as secretary of the Oxford Young Liberals and a supporter of CND. She read history at St Hilda's College (1966-69) and adored her medieval tutor, the austere and very learned Beryl Smalley, but she got on equally well with the tutor to whom she was sent out at Queen's College, Alastair Parker.

A few years in legal publishing did not really appeal. Elaine chose instead to return to Oxford for a one-year diploma in prehistoric archaeology. That probably helped her to gain a post in the British Museum's department of prehistoric and Romano-British antiquities (1975). She made many lasting friends there but perhaps sensed that her visual and design talents were not going to get their fullest expression. The director, John Pope-Hennessy, once remarked of one of her displays: "You can't make a flint look aesthetic, however hard you try."

In 1976 she moved over to the British Library – this being the time when the museum and library were still in one building. She soon became head of exhibitions, education, loans and publications, carrying off the brief with the panache and elan that were her hallmarks. The British Library was beginning to shape its own personality, and she took enormous care over its typography, rationalising gallery and exhibition labels into a single house style.

Elaine was never one to let herself be submerged by any of the institutions with which she was engaged, but she was the sort of person who liked to know their history. She could easily have been a successful lawyer, given her clear-headedness and readiness to tackle detail. This was evident in her effectiveness as chair of the library's branch of the First Division Association, the senior civil servants' union.

Her next post was as the British Library's head of art (1987-97). The management had undertaken to spend 1% of the total budget for the planned new building in Euston Road on works of art. Elaine was tenacious in seeing that this was done, whatever cutbacks the library had to endure. It is thanks to her that we can see today, for instance, the enormous bronze statue by Eduardo Paolozzi of Isaac Newton in the forecourt, the steel gates by Lida and David Kindersley, and the wonderful tapestry by RB Kitaj, If Not, Not, in the front hall.

Secondment in 1993-94 to the Department of National Heritage led to her key achievement. Given her success as secretary of the treasure trove review committee, she was asked to take on the preparation of what became the Treasure Act 1996. Many previous generations had bewailed the narrowness of the existing medieval law of treasure trove (limited, for instance, to objects that were entirely made of gold or silver), and the rise of the hobby of metal detecting had made the problem acute. The law is not yet perfect, but things are incomparably better thanks to the act and the subsequent Portable Antiquities Scheme, with several hundred newly discovered antiquities now being at least reported to the British Museum and local museums each year.

Undeterred by compulsory early retirement from the library, Elaine put to use a new range of skills which she was developing, doing pro bono work as trustee and director of the Cartoon Art Museum (1998-2003), trustee of the Institute of Historical Research (1998-2009) and fundraiser and (from 2010) council member of the Society of Antiquaries. From 2002 until her death, she was director of the Marc Fitch Fund, which supports a large number of local history and archaeological projects and publications. It is the only trust of its size and remit, and Elaine was the ideal person to help the trustees assess the merits of the multifarious appeals that are made to it.

Elaine always took delight, and an impish amusement, at exploring the lives of antiquaries of the past, conscious as she was of being the great-niece of an Oxford urban antiquary, Harry Paintin.

She is survived by her daughter, Isabel, of whom she was enormously proud.